The thin rubber button from the center of my garage remote controls broke so I made a new one from ABS that fits right into the hole.
Unscrew the case, remove any of the old rubber, drop this button in and screw case together. DONE!
Pictures show: 1) the problem 2) the button and 3) the final result.

I first tried making a complete case but that got complex with threads and mount points for the PCB and....
Decided the rest of the case was fine all I needed was a new button over the microswitch on the PCB.
Made a base plate so the button wouldn't fall out of the case and added a curved surface to the top of the button to fit nicely into the look of the existing remote.